Our hubs have ISO standard threads: 1.375"x 24 TPI (34.92mm x 1.058mm). This threading was chosen due to its compatibility with other threads used on bicycle cogs. ISO threads fit English and Italian threads almost perfectly.

Fair enough. But the next sentence says:

It is important not to switch back and forth between cogs and/or hubs with different threads.

So does that mean that Surly does not endorse taking my IRO cog off the hub it is on now (with what are presumably English 1.370"x24 threads) and placing it on their hub? I cannot imagine that the Al threads on the hub have so distorted the steel threads on the cog that it will screw up the Surly hub, but then, I'm not a mechanical engineer.

Of course, Surly offers up:

Since we only control the quality and size tolerances of all our own products, we heartily recommend using Surly cogs and Surly lockrings with Surly Hubs to assure the best fit.

I could order a Surly cog (I already have two, but not in the 17t size I prefer to commute on), and sell the IRO cog, but that's a PITA if I don't have too. I could also just go for it, since I have two fixed sides on the hub, but it would suck to ruin half of a hub on a brand new $150+ wheel.

OK, a quick call to Surly answer the question, but maybe the information will be useful to someone:

An English threaded cog works fine on their hub, regardless of where it was before. What they do not recommend doing is putting an English cog on and then replacing it with an ISO cog, because the tiny (5 thousandths) difference between the threads could cause the hub to strip. (Presumably, the same would apply to swapping back and forth between English and ISO cogs on an English-threaded hub.)

So, a revised question for the masses: Are IRO cogs English or ISO? (The IRO website doesn't say, but I haven't tried searching yet either.)

I have cut my stable down to one bike in hopes to make room for a roadie.

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I shot the service department at IRO a message asking about the threading. I'll update when I get a reply. It doesn't mention anything about threading in their shop manual online (real lame IRO). However, I would imagine it would be ISO, but that's just a guess.

Edit: I kinda doubt the .005 difference in threading would remove enough metal to cause the threads to weaken enough to strip, especially if the lockring is tightened properly, but then again that's just an opinion and I'm not the master of Surly engineering.

I shot the service department at IRO a message asking about the threading. I'll update when I get a reply. It doesn't mention anything about threading in their shop manual online (real lame IRO). However, I would imagine it would be ISO, but that's just a guess.

Edit: I kinda doubt the .005 difference in threading would remove enough metal to cause the threads to weaken enough to strip, especially if the lockring is tightened properly, but then again that's just an opinion and I'm not the master of Surly engineering.

Thanks - it'd be cool if it is ISO. I am also skeptical of the difference, but other than trying to prove them wrong, it's hard to know if Surly is talking from experience or just covering their butts.

Do not get Surly hubs. The bearings are shot after a few months, poor threading, and has a whole are not that great.

I guess I got a freaky one as it has been used for 2 years, been through 2 winters and has the original bearings, cogs thread on perfectly, never had a cog slip once and on the whole, has been an excellent hub, one that I would gladly buy again.

When sadness fills my days
It's time to turn away
And then tomorrow's dreams
Become reality to me

Got this reply today.
Thank you for your interest in Irocycle. The IRO cogs are english
threaded. Thanks.

Thanks. Of course, as a materials engineer at work point out, just how good are the tolerances on a $25 cog? The spec is 5 thousandths different, but what is the +/- that they are machined to? It could mean they are closer, or it could mean the difference is even worse.

Now I just have to decide if I drop $30 on a Surly cog and sell the IRO for $20 on eBay, or if I say the hell with it, and put it on the hub. For the $10 difference, I think peace of mind might be worth it.

I guess I got a freaky one as it has been used for 2 years, been through 2 winters and has the original bearings, cogs thread on perfectly, never had a cog slip once and on the whole, has been an excellent hub, one that I would gladly buy again.

does it have 6000 series bearings or the 7900s? surly switched to new bearings that seem to be the suck. i hate the bearings in mine, but ive never had any other problem with the hub, wish i could somehow convert it to loose ball.

Originally Posted by benda18

it's a wash when you account for the calories the prius owner uses to pass judgement on people who can see beyond the veil of greenwashed consumerism.

I have personally never owned any Surly hubs. I do however have friends that own them and the bearings in all of them have been bad news.

I also have multiple friends who work in different bike shops that have nothing good to say about them and have actually NOT let me buy them before. When multiple wrenches, whom I trust, tell me to avoid something - I do.

Now, Im sure some of their hubs are fine and will serve you very well but I would rather go with something else in the same price range based on the amount of negative things Ive heard about them and save myself time and money.